Field of the Invention
The present invention relates to an organic light emitting diode device. More particularly, the present invention relates to an organic light emitting diode device fabrication method adapted to secure design competitiveness by realizing a narrow bezel, and to an organic light emitting diode device fabricated thereby.
Discussion of the Related Art
An organic light emitting diode device is called as an organic light emitting display (OLED) device. The organic light emitting diode device emits light by forming excitons through re-combination of electrons and electric-holes, which are injected from an electron injection electrode and an electric-hole injection electrode into an organic light emission layer, and transitioning the excitons from an excited state to a ground state.
As such, the organic light emitting diode device has a self-luminous property. In other words, the organic light emitting diode device does not require any separate light source, unlike a liquid crystal display device. In accordance therewith, the organic light emitting diode device can reduce thickness and weight. Also, the organic light emitting diode device has superior features such as low power consumption, high brightness, and high-speed response. Therefore, the organic light emitting diode device attracts public attention as a next generation display device of mobile appliances. Moreover, a procedure of fabricating the organic light emitting diode device is simple. As such, fabricating cost of the organic light emitting diode device is largely reduced in comparison to that of existing liquid crystal display devices.
FIG. 1A is a perspective view showing a related art organic light emitting diode device. FIG. 1B is a cross-sectional view showing the organic light emitting diode device taken along line I-I′ in FIG. 1A.
Referring to FIGS. 1A and 1B, the related art organic light emitting diode device includes a first substrate 20, on which a light emission portion 40 is formed, and a second substrate (not shown) facing the first substrate 20. The first substrate 20 and the second substrate are combined with each other by a sealing member.
In detail, the first substrate 20 is includes a display area AA and a non-display area NA. The display area AA is used for displaying images. The non-display area NA occupies the rest of the first substrate 20 except the display area AA. A part of the non-display area NA is defined as a pad area PA.
The light emission portion 40 is formed on the display area AA. If the organic light emitting diode device is in an active matrix mode, pluralities of gate lines GL and data lines DL crossing each other are formed within the light emission portion 40. Also, a plurality of pixels is defined within the light emission portion by the pluralities of gate lines GL and data lines DL. Thin film transistors are formed at crossings of the gate lines GL and the data lines DL. Each thin film transistor is connected to a first electrode 31 which is formed within the respective pixel. An organic light emission layer 33 and a second electrode 34 are sequentially formed on the first electrode 31. In general, the first electrode 31 is used as an anode and the second electrode 34 is used as a cathode. When the second electrode 34 is formed, the light emission portion 40 is completed.
Meanwhile, a pad portion 30 is formed in the pad area PA of the non-display area NA. The pad portion 30 is connected to the gate and data lines GL and DL of the display area AA. Such a pad portion 30 connects the gate and data lines GL and DL to an external printed circuit board (not shown) which is used as a driving circuit substrate.
However, the organic light emitting diode device has a property very vulnerable to moisture and oxygen within an atmosphere. As such, the organic light emitting diode device must be encapsulated in order to prevent the intrusion of moisture and oxygen. As such, it is necessary for the organic light emitting diode device to perform an encapsulation process.
FIG. 2 is a cross-sectional view illustrating a method of fabricating an organic light emitting diode device according to the related art. In detail, FIG. 2 is a cross-sectional view illustrating a method of forming an encapsulation passivation film which is used to prevent the intrusion of moisture and oxygen.
Referring to FIG. 2, the related fabrication method of the organic light emitting diode device includes: preparing the first substrate 20 defined into the display area AA and the non-display area NA; forming the light emission portion 40 on the display area AA; forming the pad portion 30 on the pad area PA of the non-display area NA; forming an encapsulation passivation film 60 on the entire area of the first substrate 20 except the pad portion 30; and combining the first substrate 20, on which the encapsulation passivation film 60 is formed, with the second substrate (not shown).
More specifically, the formation of the encapsulation passivation film 60 includes depositing several organic and inorganic materials on the second electrode 34 of the light emission portion 40 which is used as the cathode. At this time, the encapsulation passivation film 60 is formed in such a manner as to sufficiently cover the display area AA provided with the light emission portion 40. However, the encapsulation passivation film 60 must not be formed on the pad area PA provided with the pad portion 30 which will come in contact with a driver IC (Integrated Circuit) chip and a FPC (Flexible Printed Circuit) film.
As described above, the organic light emitting diode device is vulnerable to moisture. Due to this, it is difficult to perform a wet etching process after the formation of the light emission portion 40. Therefore, a mask 1 is used to prevent the deposition of the encapsulation passivation film 60 in the pad area PA at the formation of the encapsulation passivation film 60.
The use of the mask 1 can cause many problems. For example, a fault can be caused by curling of the mask 1 or misaligning of the mask 1, quality of a formed film can deteriorate by foreign substance on the mask 1, an arc discharge can be generated in a chamber due to the mask 1, properties of a deposited film can become different by material quality of the mask 1, and static electricity can be generated due to the mask 1. Moreover, the use of the mask 1 can generate a shadow region in a deposited film and force a process margin to be reduced.
The above-mentioned problems become factors that deteriorate a yield rate of the organic light emitting diode devices. Also, the mask 1 requires an expensive fine alignment system. As such, many costs additionally needed to manufacture and maintain the expensive equipment. Moreover, the fine alignment process forces not only tact time to increase but also productivity of the organic light emitting diode devices to deteriorate. Furthermore, it is difficult for a narrow bezel to design a panel because the shadow region is generation in the deposited film.